JPH01136834A - Slip preventing device for vehicle - Google Patents

Abstract

PURPOSE:To prevent temporary increase of the drive force of drive wheels, by a method wherein gear shifting of a speed change gear is prohibited or gear shifting is effected at a speed slower than usual while a slip state is detected. CONSTITUTION:Signals from an engine rotation speed sensor 20, an airflow meter 22, an output shaft rotation speed sensor 26, and non-drive wheel rotation speed sensors 28a and 28b are inputted to an input interface 30, a central processing unit 32, and an output interface 34, with which an electronic control device 24. The electronic control device 24 calculates a slip ratio, and when the value exceeds a given value, control of lowering of an engine output is effected, and besides the gear ratio of a continuously variable speed change gear 18 is held at a value prevailing when control of lowering of an engine output is started. This constitution, since gear shifting of the continuously variable speed change gear 18 is not effected during lowering of an engine output, prevents a drive force, generated by an inertial change of an engine, from being exerted on front wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a slip prevention device for a vehicle.

(b) Conventional technology As a conventional vehicle slip prevention device, JP-A-58-38
There is one shown in Publication No. 347.

The vehicle slip prevention device shown here detects the vehicle's slip condition based on the difference between the rotational speed of the driving wheels and the rotational speed of the non-driving wheels, and stops fuel supply to the engine if the vehicle is in a slipping condition. This reduces the engine output torque, and at the same time sets the automatic transmission to a high gear position to reduce the torque transmitted to the drive wheels to prevent slippage.

Furthermore, Japanese Patent Application Laid-Open No. 60-192155 discloses a vehicle slip prevention system that changes the gear ratio of a continuously variable transmission in the direction of reducing the rotational force of the drive wheels when the drive wheels are in a slip state. Equipment is shown.

(c) Problems to be Solved by the Invention However, the conventional vehicle slip prevention device as described above has a problem in that slip increases temporarily when the transmission is shifted. That is, when slip is detected, the transmission is shifted to the smaller gear ratio side. The engine rotational speed decreases in accordance with the shift of the transmission. However, when the engine rotation speed is about to decrease, the inertia of the engine temporarily becomes a driving force and is transmitted to the driving wheels, so that the slip actually increases immediately after the shift starts. The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention solves the above problems by prohibiting the transmission from changing gears while the engine output is being reduced in order to suppress slippage. That is, the vehicle slip prevention device according to the present invention includes a slip detection device that detects that the driving wheels are in a slip state, and an engine that reduces the output of the engine when the slip detection device detects that the drive wheels are in the slip state. The engine includes an output reducing means, and a shift suppressing means for prohibiting the shifting of the transmission or making the shifting slower than usual while the engine output is being reduced by the engine output reducing means.

(E) When slip of the driving wheels is detected by the operational slip detection means, the engine output is reduced by the engine output reduction means. At the same time, the speed change suppressing means prohibits the speed change of the transmission, for example, and the transmission is fixed at the speed ratio at the time when the slip starts. As a result, the driving force transmitted from the engine to the drive wheels immediately decreases, and the slip state is released. Since the gear ratio of the transmission is held constant, the driving force is prevented from increasing temporarily due to the effect of engine inertia accompanying gear shifting.

(F) Example 7 In the vehicle 10 shown in FIG. 2, the front wheels 12 are driving wheels, and the rear wheels 14 are non-driving wheels. That is, the driving force of the engine 16 is transmitted to the front wheels 12 via the continuously variable transmission 18. The engine 16 is provided with an engine speed sensor 20 and an air flow meter 22, and signals from these are input to an electronic IJ control device 24. Further, an output shaft rotation speed sensor 26 that detects the rotation speed of the output shaft of the continuously variable transmission 18, and non-driving wheel rotation speed sensors 28a and 28b that detect the rotation speeds of the left and right rear wheels 14, respectively, are provided. , signals from these are also manually input to the electronic control device 24. The electronic control unit 24 has an input interface 30, a central processing unit 32, and an output interface 34. The electronic control device 24 outputs signals to the speed change actuator 36, the fuel injection device 38, and the ignition coil 40 of the continuously variable transmission 18, and controls their operation.

Next, the operation of the speed change control will be explained using the flowchart shown in FIG. First, the signals from each sensor are manually input in step 51), then it is determined whether the select position is in the D range or the N range (step 52), and the target gear ratio is calculated according to each range (step 53a). and 5
3b). Next, the actual gear ratio is detected (54), and a gear change command is calculated according to the deviation between the target gear ratio and the actual gear ratio (55). Next, it is determined whether the slip flag is set (see 56), and if the slip flag is not set, a shift command signal is output.
7) If the slip flag is set, the process ends without outputting the gear change command signal.

On the other hand, the engine 16 is controlled according to the flowchart shown in FIG. First, input the engine rotational speed N11: the driving wheel rotational speed V and the non-driving wheel rotational speed V.
1), then calculate the slip rate 5=(vR-VP)÷8 (62). Next, the slip rate S is a predetermined value S. If S is smaller than 30, that is, if there is no slip, the slip flag is set to 0 (68), and the process ends. On the other hand, S is S. If it is larger than , that is, if it is slipping, the slip flag is set to 1 (64), and then the target rotation speed NCUT during engine output reduction control is calculated (
65). Next, output reduction control is performed (66)
. In this engine output reduction control, the engine rotational speed is controlled to become the above-mentioned NCUT.

After all, according to the control shown in FIGS. 3 and 4 above, the slip flag is set when engine output reduction control is performed, and when the slip flag is set, the shift command signal is changed. Since there is no continuously variable transmission 1
The gear ratio No. 8 is maintained at the gear ratio at the time when the engine output reduction control was started. As a result, the continuously variable transmission 18 does not change gears while the engine output is decreasing, so there is no change in the rotational speed of the engine 16 due to the gear change of the continuously variable transmission 18, and the driving force is due to changes in the inertia of the engine 16. is prevented from acting on the front wheel 12.

Therefore, when a slip occurs, the driving force of the front wheels 12 is immediately reduced, and the slip can be suppressed.

(Second Embodiment) FIGS. 5 and 6 show a second embodiment of the present invention. The flowchart shown in FIG. 5 is similar to that shown in FIG. 3 up to step 56.

If the slip flag is set in step 56, the shift command value is corrected (step 58), and then a shift command signal is output (step 57). Further, if the slip flag is not set, a shift command signal is immediately output.

The correction of the shift command value in step 58 is, for example, 'fJ
This is done according to the pattern shown in Figure B. If the throttle opening is rapidly increased while driving along line A, the target gear ratio changes to point B, and the actual gear ratio changes accordingly. Then, as the vehicle speed increases, the gear ratio changes to the smaller side, so the gear ratio changes, for example, as shown by line E. However, when slip occurs, the rotational speed of the drive wheels rapidly increases, so the target gear ratio also changes rapidly as shown by line D.

In this case, if a slip occurs at the 0 point, step 58
limits the range of change in the speed change command. As a result, the change in the target gear ratio becomes gradual, and the gear ratio changes along line F. As a result, the gear ratio changes gradually, so it is possible to suppress changes in the engine rotational speed in almost the same way as when the gear ratio is fixed as in the first embodiment, and the same effect can be obtained. . For reference, in the first embodiment, when slip occurs at the 0 point, the gear ratio is fixed and operation is performed along line H. Note that, as shown by line G, when a slip occurs, the target gear ratio may be temporarily changed to a larger side to suppress a change in engine inertia.

Note that although the above embodiments are for the case where the transmission is a continuously variable transmission, the present invention can be similarly applied to a stepped automatic transmission.

(g) As described in detail, according to the present invention, when slippage of the driving wheels occurs, the output of the engine is reduced and the shifting of the transmission is prohibited or suppressed. It is possible to prevent the driving force of the driving wheels from temporarily increasing due to the accompanying change in engine inertia.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the constituent elements of the present invention, Fig. 2 is a diagram showing an embodiment of the invention, Fig. 3 is a diagram showing a flowchart of gear ratio control, and Fig. 4 is a flowchart of engine control. FIG. 5 is a diagram showing a flowchart of the second embodiment, and FIG. 6 is a diagram showing changes in the target gear ratio.

Claims (1)

[Claims] a slip detection device that detects that the driving wheels are in a slip state; an engine output reduction means that reduces the output of the engine while the slip detection device detects that the drive wheels are in the slip state; 1. A slip prevention device for a vehicle, comprising: a shift suppressing means that prohibits gear shifting of a transmission or makes gear shifting slower than usual while the above is detected.